To appeal to cat owners, just target their cats. And what better way to do so than with an advertisement that is literally catnip? In this diabolically clever ad campaign for Bulk Cat Litter Warehouse, Rethink Canada came up with the idea of spraying paper with catnip concentrate.

Direct mail ads were printed on the catnip-infused paper and slipped through door slots... and the cats came calling right away. Watch the kitties completely bliss out while licking, chewing, and rubbing their faces through your junk mail. [Rethink Communications via Adweek]